WASHINGTON (AP) - Airline pilots spend nearly all their time monitoring automated cockpit systems rather than "hand-flying" planes, but their brains aren't wired to continually pay close attention to instruments that rarely fail or show discrepancies.

As a result, pilots may see but not register signs of trouble, a problem that is showing up repeatedly in accidents and may have been a factor in the recent crash landing of a South Korean airliner in San Francisco, industry and government experts say.

Teaching pilots how to effectively monitor instruments has become as important as teaching them basic "stick-and-rudder" flying skills, a panel of experts told an annual safety conference of the Air Line Pilots Association, the world's largest pilots union, on Wednesday.

"The human brain just isn't very well designed to monitor for an event that very rarely happens," said Key Dismukes, a top NASA human factors scientist.

While people "do very well" at actively controlling a plane, "we're not well designed to monitor for a little alphanumeric (a combination of alphabet letters and numbers) on the panel even if that alphanumeric tells us something important," he said. "We can't just sit there and stare at the instruments."

The "sheer volume of monitoring required even on the most routine flights and the diversity" of systems that must be monitored has increased, he said.

Concern about the problem is great enough that government, union and industry safety officials formed a working group last fall to come up with a blueprint for teaching pilots techniques for how to overcome the brain's natural tendency to sometimes see but disregard important information. For example, if pilots see airspeed indicators showing appropriate speeds landing after landing, their brains may filter out an unexpected low or high speed, they said.

"The human brain filters out information it considers unchanging," said Helena Reidemar, an airline pilot and the pilots union's director of human factors.

Asiana Flight 214 crashed short of a runway at San Francisco International Airport on July 6 after a nearly 11-hour flight from Seoul, South Korea. Of the 307 people on board, three have died and dozens of others were injured. One of the issues that have emerged in the National Transportation Safety Board's investigation of the accident is whether the pilots, who were supposed to be watching airspeed indicators, were aware the plane was traveling at speeds so dangerously slow that it was at risk of losing lift and stalling.

The flight's pilots set a target airspeed of 137 knots for crossing the runway's threshold. The plane reached speeds as low as 103 knots just before its landing gear and then its tail collided with a rocky seawall at the end of the runway, shearing off the tail, dumping three flight attendants onto the tarmac and sending the rest of the plane spinning and sliding.

Dismukes cautioned that it's too soon to reach conclusions about whether the three Asiana pilots who were in the Boeing 777's highly-automated cockpit were closely monitoring the plane's airspeed, "but what was going on there in terms of monitoring systems obviously is going to be a crucial issue."

Robert Sumwalt, an NTSB board member, said: "The question is, did the pilots recognize they were slow? And if not, why not?"

The board's investigation hasn't turned up any mechanical or computer problems with the plane, NTSB chairman Deborah Hersman said at briefing last week.

The board has repeatedly investigated accidents in which pilots' failure to closely monitor key systems contributed to the crash, Sumwalt said.

In 2007, after an investigation of a fatal business jet accident in Pueblo, Colo., the board recommended that the Federal Aviation Administration require that pilot training programs be modified to contain segments that teach and emphasize monitoring skills and how to manage multiple tasks, Sumwalt said. Since then, the board has twice repeated the recommendation in response to other accidents, he said.

The FAA, however, hasn't required airlines to change their training programs, Sumwalt said. Instead, the agency suggested airlines revise their procedures to "promote effective monitoring" if pilots are found to be inconsistent in their monitoring techniques, he said.

One of the accidents that led NTSB to renew its recommendation was the February 2009 crash of a regional airliner near Buffalo, N.Y. In that case, the two Colgan Air pilots weren't closely monitoring the Bombardier Q-400's airspeed and so failed to notice that the plane's speed had rapidly dropped about 50 knots, Sumwalt said. The startled captain responded incorrectly to an automated warning of an impending stall, sending the plane plunging into a house below. Fifty people, including a man on the ground, were killed.

"This is an area that is really ripe for improving safety," he said. "It's time for a paradigm shift. ... It used to be pilots were judged on their stick-and-rudder skills. They also should have to have good monitoring skills."

Some airlines are incorporating those techniques for improving monitoring skills in their training, experts said.

"We understand there is a threat. We understand there is a need to do things better," said Christopher Reed, a JetBlue Airways captain and pilot training manager who was a member of the panel.

JetBlue is trying to give pilots more time flying planes without relying on automated systems in part "because the mental habit patterns you are following by practicing those skills can help you be a better monitor," he said.

Several panel members emphasized the importance of "actively monitoring" versus "passively monitoring" cockpit systems. Pilots who are flying without automated systems are mentally engaged in flying, and they need to bring that same awareness to monitoring, experts said.